Method, apparatus and system for placing emergency calls from a vehicle

ABSTRACT

A system, apparatus, and method are provided for placing emergency calls from a vehicle to a Public Safety Answering Point. An emergency call apparatus is configured to detect a trigger condition and, if the trigger condition is detected, send a telephone dial command through a vehicle communication network to a telecommunication apparatus to establish voice communication with the Public Safety Answering Point. A method is provided of retrofitting a vehicle with embedded telecommunication apparatus to enable single button access to emergency services without the need for a fee based subscription.

TECHNICAL FIELD

The present disclosure relates to a method, apparatus and system forestablishing emergency communication from a vehicle and, morespecifically, to a system for and a method of initiating a wirelessemergency telephone call through a vehicle data bus.

BACKGROUND OF THE INVENTION

Being able to easily alert emergency responders in case of an automobileaccident is highly desirable. Mobile application service providers (suchas OnStar®) address this need for their subscribers by offering anemergency call button located within reach of the driver of anautomobile. Upon pressing the emergency call button an emergencytelephone call is placed from a cellular telephone which is embedded inthe vehicle through a wireless telecommunication network and a publicswitched telephone network to a service center operated by the mobileapplication service provider. An emergency call to the service providermay also be initiated automatically, e.g. upon airbag deployment.

In case of an incoming emergency call the mobile application servicecenter silently obtains vehicle position information, e.g. informationfrom a GPS receiver that is also embedded in the vehicle. The mobileapplication service center as part of an emergency assistance serviceinforms public safety authorities of the emergency and conveys thevehicle's position. The emergency assistance service is typicallyavailable only to those who register (for a fee) with the mobileapplication service provider. Registration with the mobile applicationservice providers includes an underlying registration with the wirelesstelecommunication network. Several elements of one such system aredescribed in U.S. Pat. No. 6,812,832 (Lobaza), which is herebyincorporated by reference.

The embedded cellular telephone may also be used to place hands freetelephone calls. Dialing the embedded cellular telephone may utilize aspeech recognition engine that is capable of recognizing spokentelephone numbers or voice tags associated with telephone numbers. Tofacilitate dialing the embedded cellular telephone may also be connectedto an external keypad, e.g. a telephone-style keypad located in thevehicle's dashboard or a virtual keypad displayed on a touch screendisplay. The external keypad may communicate with the embedded cellulartelephone by sending a telephone dial command message through thevehicle communication network. The embedded cellular telephone isaccordingly configured to receive telephone dial command messages on thevehicle communication network and establish a telephone call to therequested telephone number.

US law obligates commercial mobile radio service providers to transmitall wireless 911 emergency calls without respect to their callvalidation process to a Public Safety Answering Point (PSAP), or, whereno Public Safety Answering Point has been designated, to a designatedstatewide default answering point or appropriate local emergencyauthority. The law extends to voice capable cellular telephones embeddedin vehicles. An embedded cellular telephone can hence be used in anemergency to directly alert public safety authorities by dialing 911regardless of registration status with the mobile application serviceprovider or the underlying wireless telecommunication network. However,the user interface provided to dial 911 is inferior to single buttonactivation and may e.g. require use of the voice recognition interface.Changes in an operator's voice during an emergency frequently cause thevoice recognition engine to fail detecting a spoken “dial 9-1-1” commandand thereby preclude the operator from receiving the help he is seeking.

What is therefore needed is a method for combining the benefits oflegally mandated free wireless 911 access to a Public Safety AnsweringPoint with the advantageous single button user interface for placingemergency calls to a mobile application service center.

SUMMARY OF THE INVENTION

In one aspect of the present invention an integrated vehiclecommunication system includes a telecommunication apparatus incommunication with a vehicle data bus. An emergency call apparatus isalso in communication with the vehicle data bus, the emergency callapparatus further providing an emergency call push button switch toinitiate an emergency telephone call to a Public Safety Answering Point.When the emergency call push button switch is pressed the emergency callapparatus transmits a telephone dial command message including atelephone number to be dialed on the vehicle data bus. Thetelecommunication apparatus is configured to receive the telephone dialcommand and establish communication with the requested telephone number.To initiate an emergency call to a Public Safety Answering Point in theUnited States the emergency call apparatus may e.g. transmit a telephonedial command message requesting the telecommunication apparatus to dial“911”.

In a further aspect the emergency call apparatus may include an inputfor an external switch. In this aspect the emergency call push buttonswitch may be remote from the emergency call apparatus and may e.g. belocated within reach of the driver of the vehicle whereas the emergencycall apparatus may be located somewhere else hidden in the vehicle.

In another aspect the emergency call apparatus may be added to thevehicle during a retrofit. In this aspect the vehicle may be originallyequipped with an embedded telecommunication apparatus and an emergencycall push button switch connected thereto. Before the retrofit pressingthe emergency call button is detected by the telecommunication apparatuswhich responsive to the button press initiates an emergency call to amobile application service center.

During the retrofit an emergency call apparatus is added to the vehicle.The electrical connection between the emergency call push button switchand the telecommunication apparatus is separated and the emergency callpush button switch is rewired and connected to the emergency callapparatus.

After the retrofit pressing the emergency call push button is detectedby the emergency call apparatus which responsive to the button presstransmits a telephone dial command message on the vehicle data bus. Thetelephone dial command message may request the telecommunicationapparatus to dial the telephone number 911. The telecommunicationapparatus responsive to receiving the telephone dial command messageestablishes a voice call to a Public Safety Answering Point.

In yet another aspect the emergency call apparatus may be configured todetect a trigger condition and responsive thereto request thetelecommunication apparatus to establish communication with a PublicSafety Answering Point. The trigger condition may be a manual emergencycall push button press. As part of an automatic emergency calling systemthe trigger condition may also be the receipt of one or more messages onthe vehicle data bus which are reflective of a vehicle accident, e.g. amessage signaling airbag deployment. Upon detecting a trigger conditionthe emergency call apparatus may transmit a telephone dial commandmessage on the vehicle data bus requesting the telecommunicationapparatus to dial 911. The telecommunication apparatus responsive toreceiving the telephone dial command message establishes a voice call toa Public Safety Answering Point.

In still another aspect the emergency call apparatus may provide anelectrically controlled switch to separate the vehicle communicationnetwork into two subnets. One subnet may be used to communicate betweenthe emergency call apparatus and the telecommunication device and theother subnet may be used to communicate between the emergency callapparatus and the rest of the vehicle. This aspect can compensate forpossible loss of communication on the vehicle data bus after a vehiclecrash, e.g. because a wire within the communication network is shortedto ground or battery as a result of the crash. The emergency callapparatus may be configured to detect loss of communication andresponsive thereto open the electrically controlled switch, therebydividing the communication network into the two electrically insulatedsubnets. In result the emergency call apparatus separates the damagedportion of the vehicle communication network from its connection to thetelecommunication apparatus and thereby regains its ability tocommunicate with the telecommunication apparatus and initiate anemergency call even though communication with the rest of the vehicle isno longer possible.

In yet another aspect the emergency call apparatus may provide twovehicle data bus interfaces wherein the first interface is used tocommunicate with the telecommunication apparatus and the secondinterface is used to communicate with the rest of the vehicle. In thisaspect the emergency call apparatus acts as a bi-directional gatewaybetween the two vehicle data bus interfaces. Messages which theemergency call apparatus receives through the first vehicle data businterface are retransmitted through the second vehicle data businterface. Vice versa messages received through the second vehicle databus interface are retransmitted through the first vehicle data businterface. The two vehicle data bus interfaces are electricallyinsulated from each other such that the emergency call apparatusmaintains its ability to communicate with the telecommunicationapparatus even if communication with the rest of the vehicle can not beestablished, e.g. because a communication bus wire is shorted to groundor battery as may happen during an accident.

The following detailed description of the invention is merely exemplaryin nature and is not intended to limit the invention or the applicationand uses of the invention. Furthermore, there is no intention to bebound by any theory presented in the preceding background of theinvention or the following detailed description of the invention.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an exemplary wireless and a publicswitched telecommunication network through which emergency calls can beplaced from a vehicle to a service center or Public Safety AnsweringPoint.

FIG. 2A is a block diagram illustrating the vehicle portion of awireless communication system for placing emergency calls used in thevehicle of FIG. 1.

FIG. 2B is a block diagram showing aspects of a prior art vehiclecommunication system for communicating with a mobile application servicecenter before retrofit with an emergency call apparatus.

FIG. 2C is a block diagram showing aspects of a vehicle communicationsystem for communicating with a Public Safety Answering Point afterretrofit with an emergency call apparatus.

FIG. 3 is a block diagram illustrating a vehicle communication systemshowing an airbag control apparatus, a telecommunication apparatus, anemergency call apparatus and a navigation system communicating through acommon vehicle data bus.

FIG. 4 is a block diagram illustrating an alternative embodiment of avehicle communication system in which the telecommunication apparatus isconnected to the vehicle data bus through the emergency call apparatus.

FIG. 5 is a block diagram illustrating an exemplary embodiment of anemergency call apparatus for a vehicle communication systemconfiguration as shown in FIG. 3.

FIG. 6 is a block diagram illustrating an exemplary embodiment of anemergency call apparatus for a vehicle communication systemconfiguration as shown in FIG. 4.

FIG. 7 is a block diagram of an alternative embodiment of the emergencycall apparatus show in FIG. 6.

FIG. 8 is a flow diagram illustrating an exemplary method for initiatingan emergency call.

FIG. 9 is a flow diagram illustrating an alternative embodiment of themethod shown in FIG. 8.

FIG. 10 is a schematic diagram of an exemplary touch screen display.

DETAILED DESCRIPTION

Referring to FIG. 1, there is shown a vehicle 100 featuring a mobiletelecommunication apparatus, suitable for use with an embodiment of theinvention, and which may be installed in the vehicle or carried into thevehicle by the subscriber. The mobile telecommunication apparatuscommunicates through a wireless network 102, symbolized by a localtelecommunication antenna tower, with a public switched telephonenetwork (PSTN) 104, to which are also connected telephones 110 and 112.Wireless network 102 may also communicate with other wirelesstelecommunication devices, here symbolized by a wireless telephone 114.The mobile telecommunication apparatus in vehicle 100, which will bedescribed in more detail with reference to FIG. 2A, may include acellular telephone or any other wireless device that may be registeredwith a cellular service provider providing general dialing capability inconnection with, and operation through, PSTN 104. It may also include acellular telephone or other wireless device that is not or that is nolonger registered with a cellular service provider so long as itprovides connection with and operation through PSTN 104 with a PublicSafety Answering Point (PSAP) 106.

The telecommunication apparatus carried in vehicle 100 may have beendesigned to provide access to mobile application services of a serviceprovider such as, for example, OnStar®. Mobile application services aretypically provided within a subscription business model, which requirespayment of a subscription fee per period, e.g. $19.95 per month or $199per year. The telecommunication apparatus may have been permanentlyinstalled in the vehicle at the time of vehicle assembly and the cost ofthe telecommunication apparatus may have been subsidized by the serviceprovider in anticipation of future subscription revenue if the owner orlessor of vehicle 100 registers for mobile application services. Theservice provider generally maintains at least one service center 108,which is connected to PSTN 104 and which the subscriber and othersubscribers in other vehicles call for the mobile application services.The mobile application services may include, for example, requests forvehicle location, selection of specific points of interest anddirections thereto, and emergency assistance (both requested andautomatic), as well as others not named.

If the owner or lessor of vehicle 100 does not register with the serviceprovider, e.g. to avoid the financial burden associated with asubscription, the service provider may refuse to provide mobileapplication services including emergency assistance. The mobileapplication service provider may also deactivate the telecommunicationapparatus located within vehicle 100. Deactivating the telecommunicationapparatus may include deregistering the cellular telephone therein fromwireless network 102 so that the telecommunication apparatus can nolonger gain access to wireless network 102 for general dialing and canthus no longer connect to service center 108.

Even if the telecommunication apparatus within vehicle 100 has beendeactivated and the cellular telephone therein been deregistered fromwireless network 102 both can still be used to establish a connection toa Public Safety Answering Point (PSAP). Connecting to a PSAP isindependent of a subscription with the service provider or theunderlying wireless network 102. This is, especially in the UnitedStates, to comply with federal law mandating free access to a PSAP forall devices used to access a commercial mobile radio service (CMRS).

Referring now to FIG. 2A there is shown wireless telecommunicationapparatus 200 in vehicle 100. The telecommunication apparatus 200communicates voice and data through an antenna 206 with wireless network102 and through wireless network 102 with public switched telephonenetwork 104. The telecommunication apparatus 200 may provide“hands-free” voice communication through a microphone 202 and speaker204. The telecommunication apparatus may include a GPS or similarnavigation apparatus (not shown) which receives signals through a GPSantenna (not shown) from global positioning satellites and derivestherefrom position data (e.g., the longitude and latitude and/or thespeed and heading) of the apparatus. The telecommunication apparatus 200may convert the GPS position information into a transmissible form forsubsequent transmission from vehicle 100 to service center 108 or PublicSafety Answering Point 106. Communication between the telecommunicationapparatus 200 and service center 108 or PSAP 106 may be voicecommunication utilizing microphone 202 and speaker 204 and/or datacommunication the data comprising e.g. GPS location information.

Connected to the telecommunication apparatus 200 are one or more buttons208 and status indicator 210. Buttons 208 provide a simple userinterface for an operator, e.g. the driver or passenger in vehicle 100,to interact with the telecommunication apparatus 200. The buttons 208may e.g. include a dedicated emergency call button. If the emergencycall button is pressed telecommunication apparatus 200 establishes voiceand/or data communication with service center 108. Status indicator 210,which may e.g. be one or more light emitting diodes or any other form ofdisplay, provides feedback to the vehicle operator as to the status ofthe telecommunication apparatus 200. Telecommunication apparatus 200 isalso connected to vehicle data bus 212 to exchange messages with otherelectronic modules within vehicle 100 as required.

Telecommunication apparatus 200 may provide general dialing capability,e.g. to a telephone 110, 112 within the public switched telephonenetwork 104 or to a wireless telephone 114 through wireless network 102or any other wireless network. To facilitate dialing telecommunicationapparatus 200 may include a voice recognition and activation apparatus,which responds to predetermined spoken data via microphone 202 toperform predetermined functions. It accesses a plurality of voice modelsstored within telecommunication apparatus 200. Each voice model includesdata permitting recognition of a spoken word or phrase. The voicerecognition apparatus compares received spoken data with the voicemodels in order to recognize those words and phrases which are definedand for performing predetermined actions in response thereto. Some voicemodels represent commands, such as “menu,” “store,” “dial,” “call,” etc.Other voice models represent the digits required for telephone dialing:“one,” “two,” etc. For example, the apparatus may be programmed torecognize the phrase “Dial 9-1-1 Dial” and respond by placing a call toa Public Safety Answering Point. General dialing capability may beinitiated by the word “Dial” followed by the number, digit by digit.

Telecommunication apparatus 200 may also be configured to allow dialingutilizing a keypad which may be connected directly to communicationapparatus 200 or indirectly connected to another module whichcommunicates with telecommunication apparatus 200 through the vehicledata bus 212. In an exemplary embodiment navigation system 218 comprisesa touch screen display 220 which displays a virtual telephone keypad222. An operator may enter a telephone number he wishes to dial on thevirtual keypad 222. After the telephone number has been enterednavigation system 218 transmits a telephone dial command message on thevehicle data bus 212 including the telephone number to be dialed.Telecommunication apparatus 200 responsive to receiving the telephonedial command message establishes voice and/or data communication withthe desired telephone number.

Quicker and easier access to dialing 911 and establishing voice and/ordata communication with a Public Safety Answering Point is provided byemergency call apparatus 214, which is connected to vehicle data bus 212and to one or more buttons 216. Buttons 216 may include an emergencycall push button switch which when pressed causes emergency callapparatus 214 to transmit a telephone dial command message including atelephone number to be dialed on vehicle data bus 212. Telecommunicationapparatus 200 responsive to receiving the telephone dial command messageestablishes voice communication with the requested telephone number,e.g. 911. Emergency call apparatus 214 and its operation are describedin more detail with reference to FIGS. 5 through 9 below.

As is shown in FIG. 2B vehicles equipped with an embeddedtelecommunication apparatus 200 are typically also equipped with buttons208, one of which may be an emergency call button to initiate anemergency call to service center 108. Buttons 208 and telecommunicationapparatus 200 do not serve any useful purpose if the owner or lessor ofvehicle 100 does not register with the mobile application serviceprovider. The existing buttons 208 and the telecommunication apparatus200 may however be used when retrofitting vehicle 100 with an emergencycall apparatus 214 at some time after vehicle built.

An exemplary method of retrofitting vehicle 100 is show in FIG. 2C.Vehicle 100 is retrofitted by adding emergency call apparatus 214. Theelectrical connection between buttons 208 and telecommunicationapparatus 200 is removed and instead buttons 208 are rewired andconnected to emergency call apparatus 214. Optionally the vehicle databus connection between telecommunication apparatus 200 and vehicle databus 212 may be disconnected and instead re-routed into the emergencycall apparatus 214. A new connection is made between the emergency callapparatus 214 and vehicle data bus 212. Further, emergency callapparatus 214 is connected to vehicle battery and vehicle ground topower emergency call apparatus 214.

To enable the rewiring of buttons 208 the electrical interface betweenbuttons 216 and emergency call apparatus 214 may be identical to theelectrical interface between buttons 208 and telecommunication apparatus200. Using an identical interface, e.g. the same resistor values in caseof resistor coded switches, provides that an emergency call button 208which is connected to and used in combination with telecommunicationapparatus 200 before the retrofit can be rewired and used in combinationwith emergency call apparatus 214 after the retrofit. This simplifiesthe process of retrofitting vehicle 100 which may have originally beenequipped with telecommunication apparatus 200 and buttons 208 but notemergency call apparatus 214 and buttons 216.

Referring now to FIG. 3, there is shown a block diagram illustrating anexemplary vehicle communication system 300 including thetelecommunication apparatus 200, an airbag control apparatus 302, theemergency call apparatus 214 and the navigation system 218. As is shown,each system is in communication with the vehicle's data bus 212, whichmay be a Class 2 or CAN vehicle data bus or any other suitable bus knownin the art for electronic data communication.

FIG. 4 illustrates an alternative embodiment of the vehiclecommunication system 400. In this embodiment telecommunication apparatus200 is in communication with vehicle data bus 212 using an indirectconnection made trough emergency call apparatus 214, as will beexplained in more detail with respect to FIG. 6 and FIG. 7.

FIG. 5 is a block diagram illustrating an exemplary emergency callapparatus 214. Control processor 500, which may take the form of aprogrammed digital computer or a custom digital processor, isoperatively connected to push button switch 216. Push button switch 216may be an emergency call button located within easy reach of the driverand labeled prominently, e.g. with a Red Cross icon or the letters“SOS”. Push button switch 216 is designed to be easily found andoperated by the driver or passenger of vehicle 100 even under stress.Push button switch 216 may be any suitable device that translates ahuman operator's intention into a signal that can be detected by controlprocessor 500, including e.g. a momentary push button switch, a toggleswitch, a rocker switch, a rotary switch or a virtual button on a touchscreen display. Control processor 500 is connected to the vehicle databus 212 through a vehicle data bus interface 504 using an electricalterminal 508. Control processor 500 and vehicle data bus interface 504are powered by power supply 506. Power supply 506 is connected to thevehicle's power distribution system through vehicle battery terminal 512and vehicle ground terminal 510. While emergency call apparatus 214 isshown as a stand alone unit it should be appreciated that it may also beintegrated within another electronic control module in which casecontrol processor 500, power supply 506 and vehicle data bus interface504 may be shared with other functions.

FIG. 6 is an alternative embodiment showing an emergency call apparatus610 which may be used in the vehicle communication system 400 shown inFIG. 4. In this example the telecommunication apparatus 200 is connectedto the vehicle data bus 212 indirectly through emergency call apparatus610. Electrical terminal 600 connects the emergency call apparatus 610to the telecommunication communication apparatus 200. Electricalterminal 602 connects the emergency call apparatus 610 to vehicle databus 212 and through that to all other electronic modules communicatingthrough vehicle data bus 212. Control processor 500 electronicallycontrols switch 606, which may e.g. be an electromechanical relay withcoil 604, or any other suitable switching device. Switch 606 is normallyclosed, creating a short circuit between electrical terminals 600 and602. In case of a crash the vehicle communication system 400 may bedamaged, e.g. may deformation to the vehicle's sheet metal have caused awire of vehicle data bus 212 to be shortened to vehicle ground orbattery, making communication on vehicle data bus 212 impossible.Control processor 500 is configured to detect such damage to thecommunication system by monitoring its vehicle data bus interface 504.If damage to the communication system is detected control processor 500restores communication with the telecommunication device 200 by openingswitch 606 and thereby disconnecting the damaged part of the vehiclecommunication system 400 from vehicle data bus interface 504. In itsopen position switch 606 may cause vehicle data bus interface 504 to beconnected to a network termination element 608, simulating a networktermination usually present in the now disconnected vehiclecommunication system. Network termination may consist of a pull-up orpull-down resistor or any other electronic circuit known in the art ofelectronic communication for terminating communication networks.

FIG. 7 shows another alternative embodiment of emergency call apparatus710. In this example control processor 500 communicates withtelecommunication apparatus 200 through vehicle data bus interface 504and electrical terminal 600. It is also communicates with otherelectronic modules connected to the vehicle data bus 212 through asecond vehicle data bus interface 700 and electrical terminal 602.Vehicle data bus interface 504 and vehicle data bus 700 are electricallyinsulated from each other so that damage to the vehicle data bus 212does not affect the ability of control processor 500 to communicate withthe telecommunication device 200 through vehicle data bus interface 504.During normal operation control processor 500 is configured to act asbidirectional gateway between vehicle data bus interface 504 and vehicledata bus 700. Control processor 500 re-transmits any messages itreceives from vehicle data bus interface 504 through vehicle data businterface 700 and any messages it receives from vehicle data businterface 700 through vehicle data bus interface 504, therebyfunctionally connecting telecommunication apparatus 200 with vehicledata bus 212.

FIG. 8 is a flow diagram illustrating an exemplary method 800 that maybe implemented in process controller 500. Process controller 500 isconfigured to detect a trigger condition in block 802. The triggercondition may be a manual operator request to initiate an emergencycall, e.g. by pressing emergency call push button switch 216. Thetrigger condition may also be the receipt of a predetermined message ora combination of predetermined messages on vehicle data bus 212. Thepredetermined message or messages may e.g. reflect that the airbagcontrol apparatus 302 has inflated an airbag in vehicle 100. Othersuitable messages that may act as a trigger for automatic emergencycalling include a message from an object detection apparatus indicatingthat vehicle 100 was involved in a collision, a message indicatingvehicle deceleration above a predetermined threshold or any othermessage or combination of messages which indicate that vehicle 100 wasinvolved in a severe accident which may have caused the occupants withinvehicle 100 to be injured and no longer be able to manually initiate anemergency call.

If the trigger condition in block 802 is detected then in step 804process controller 500 sends a telephone dial command message to thetelecommunication apparatus 200. The telephone dial command consists ofor is part of a predetermined message on the vehicle data bus containinga telephone number to be dialed. Telecommunication apparatus 200 isconfigured to receive the telephone dial command and responsive theretoestablish voice and/or data communication through wireless network 102and PSTN 104 with the desired telephone number. For emergency use in theUnited States the telephone number requested in step 804 will typicallybe “911” to establish communication with a PSAP.

As described earlier with respect to FIG. 2B and FIG. 2C emergency callapparatus 214 may be retrofitted into a vehicle 100 at some time afterthe vehicle has been built. In case of a retrofit telecommunicationapparatus 200 may not haven been designed for use with the emergencycall apparatus 214. In particular, telecommunication apparatus 200 maynot have been configured to receive a telephone dial command message onvehicle data bus 212 that is originating from emergency call apparatus214. Telecommunication apparatus 200 may however have been configured toreceive telephone dial command messages on vehicle data bus 212 that areoriginating from other devices, for example navigation system 218. Tooperate under these circumstances emergency call apparatus 214 may beconfigured to mimic the telephone dial command message originating e.g.from navigation system 218. To mimic the dial command message emergencycall apparatus 214 uses the same message identifier segment that hasbeen assigned to navigation system 218 when transmitting its telephonedial command message. By sharing the same message identifier segment atelephone dial command message originating from emergency call apparatus214 and a telephone dial command message originating from navigationsystem 218 become indistinguishable for the telecommunication apparatus200. Telecommunication apparatus 200 hence responds properly to atelephone dial command message originating from emergency call apparatus214 even though it may not have been designed for this purpose. Whileemergency call apparatus 214 shares the same message identifier segmentwith navigation system 218 it should be understood that vehicle 100 neednot necessarily be equipped with navigation system 218. It is sufficientif telecommunication apparatus 200 is configured to respond to telephonedial command messages on the vehicle data 212 bus irrespective ofwhether the potential transmitter of such a message is actually presentin the vehicle.

Table 1 illustrates the structure of an exemplary vehicle data busmessage. As illustrated the message consist of an identifier segment,which in case of CAN messages may e.g. be 11 or 29 bits long, and a datasegment carrying the message payload, which may be up to 8 bytes long.To avoid message collision vehicle communication networks usually useunique identifier segments for each transmitting module, if the samemessage is originating from more than one module. Modules connected tothe communication network are configured to respond to predeterminedmessages which are distinguished from other messages by their identifiersegments.

TABLE 1 Identifier Segment Data Segment 11 bit or 29 bit 0 to 8 bytesExample 0x0CF00400 39 31 31 23 FF FF FF FF

To avoid the unlikely but possible collision of two telephone dialcommand messages issued simultaneously by both the navigation system 218and the emergency call apparatus 214 the emergency call apparatus 214may in a vehicle communication system configuration 400 actively preventsuch collision. Accordingly control processor 500 in an embodiment asshown in FIG. 6 may in a first step open switch 606 so that thenavigation system 218 is no longer connected to the telecommunicationapparatus 200 before control processor 500 in a second step transmitsits telephone dial command message to the telecommunication apparatus200. Control processor 500 in an embodiment as shown in FIG. 7 mayselectively suppress forwarding a telephone dial command received fromthe navigation system 218 through vehicle data bus interface 700 whiletransmitting its own telephone dial command through vehicle data businterface 504.

FIG. 9 is a flow diagram showing an alternative exemplary embodiment ofthe method illustrated in FIG. 8. This embodiment is suitable forexample for vehicles in which the emergency call apparatus 214 isintegrated with the navigation system 218 and where the navigationsystem 218 is connected to a display. If in step 802 a triggercondition, e.g. an airbag deployment, is detected the emergency callapparatus displays or causes to be displayed an emergency screen 1000comprising a prominent user interface to activate an emergency call. Ifin step 904 an emergency call is requested the emergency call apparatusin step 804 sends a telephone dial command to telecommunicationapparatus 200.

Finally, an exemplary emergency screen 1000 as may e.g. be used within atouch screen navigation display is shown in FIG. 10. Emergency screen1000 comprises virtual button 1002 to call PSAP 106 and virtual button1004 to call service center 108.

While the invention has been described with reference to a preferredembodiment(s), it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment disclosed as the best modecontemplated for carrying out this invention, but that the inventionwill include all embodiments falling within the scope of the appendedclaims.

What is claimed is:
 1. A method for retrofitting a vehicle comprising atelecommunication apparatus connected to a vehicle data bus and a pushbutton switch connected to the telecommunication apparatus the methodcomprising: adding an emergency call apparatus to the vehicle;connecting the emergency call apparatus to the vehicle data bus;separating the electrical connection between the push button switch andthe telecommunication apparatus; and connecting the push button switchto the emergency call apparatus.
 2. The method of claim 1 wherein theemergency call apparatus responsive to pressing the push button switchtransmits a message on the vehicle data bus.
 3. The method of claim 2wherein the message on the vehicle data bus causes the telecommunicationapparatus to establish communication with a public safety answeringpoint.
 4. The method of claim 2 wherein the message comprises anidentifier segment and a data segment and wherein the data segmentcomprises a telephone number.
 5. The method of claim 2 wherein themessage comprises an identifier segment and a data segment and whereinthe identifier segment is shared between the emergency call apparatusand another apparatus for communicating on the vehicle data bus.